The present invention relates to driving circuitry for solenoids and the like, and more particularly to the voltage regulator portion of such circuitry.
A number of criteria must be considered in designing suitable circuitry for driving a solenoid or similar electronic device. The circuit designer must determine the range of output currents, voltages, and other output parameters required by the application in question. In order to minimize internal heating, it is furthermore desirable to utilize a high efficiency design.
A particular application requiring circuitry of this type is disclosed in commonly assigned copending patent application Ser. No. 296,757 which discloses apparatus for severing and stacking tickets incorporating a single solenoid to drive the various moving parts. In the preferred embodiment of this apparatus, the solenoid is operated at low duty cycle with high pulse current input. These particular characteristics in addition to the general criteria above mentioned are not satisfied in the prior art.
The voltage regulation section of such drive circuitry is particularly critical to its operation. This type of circuitry is discussed in The Voltage Regulation Handbook, compiled by the Engineering Staff of Texas Instruments, Inc. (1977). This reference discloses a variety of voltage regulator types, including "switching" regulators. None of the regulators disclosed, however, provide reliable high-power outputs with low power dissipation.
Accordingly, it is a primary object of the invention to provide voltage supply circuitry which yields output signals over a wide range of voltages and currents. A related object is that such circuitry be particularly suited to applications demanding low duty cycles and high pulse currents.
Another object of the invention is to achieve circuitry of this type having high efficiency. A related object is the reduction of internal heating.
A further object of the invention is that such circuitry be designed with reference to various economic factors. A related object is the provision of apparatus having relatively few parts and a low cost of manufacture. Yet another related object is the achievement of compact drive circuitry.
Still another object of the invention is the provision of precise line regulation in such circuitry.